Evidence for a receptor-activated Ca2+ entry pathway independent from Ca2) store depletion in endothelial cells.

Ca(2+) entry in endothelial cells is a key signaling event as it prolongs the Ca(2+) signal activated by a receptor agonist, and thus allows an adequate production of a variety of compounds. The possible routes that lead to Ca(2+) entry in non-excitable cells include the receptor-activated Ca(2+) entry (RACE), which requires the presence of an agonist to be activated, and the store-operated Ca(2+) entry (SOCE) pathway, whose activation requires the depletion of the ER Ca(2+) store. However, the relative importance of these two influx pathways during physiological stimulation is not known. In the present study we experimentally differentiated these two types of influxes and determined under which circumstances they are activated. We show that La(3+) (at 10 microM) is a discriminating compound that efficiently blocks SOCE but is almost without effect on histamine-induced Ca(2+) entry (RACE). In line with this, histamine does not induce massive store depletion when performed in the presence of extracellular Ca(2+). In addition, inhibition of mitochondrial respiration significantly reduces SOCE but modestly affects RACE. Thus, agonist-induced Ca(2+) entry is insensitive to La(3+), and only modestly affected by mitochondrial depolarization. These data shows that agonist relies almost exclusively on RACE for sustained Ca(2+) signaling in endothelial cells.

[Hemiplegia and a hiking tour of Mont Blanc: from hope to reality]. / Hémiplégie et tour du Mont Blanc: de l'espoir à la réalité.

INTRODUCTION: At the end of an endurance training program for stroke patients with hemiplegia, we offered a hiking tour around the Mont Blanc Pedestrian Tour. We found no publication describing a similar experience and no scientific data in the literature to determine the physiological characteristics required for this performance, particularly regarding cardiac and vascular capacities, level of impairment, and functional abilities. OBJECTIVE: To complete a part of the Mont Blanc Pedestrian Tour over six days, with a group of adults with hemiparesis and aphasia due to stroke. POPULATION: Seven of 20 subjects with right hemiparesis and aphasia were selected on the basis of results of physiological tests, after an endurance training program and two tests hikes at medium altitude. Mean age was 51.71 +/- 7.13 years, mean VO(2max) 19.76 +/- 3.46 ml.g(-1).mm(-1), mean P(max) 90 +/- 22.68 and mean walking speed 3.60 +/- 1.30 km/hour. ORGANIZATION: Organization involved setting up the itinerary, recruiting accompanying personnel (9 people), and arranging security. No specific adaptations for accessibility were available, and no specific equipment was used, except for standard walking sticks. RESULTS: During this pedestrian tour, the subjects demonstrated strong motivation, as well as exceptional physical and functional performance, despite significant changes in elevation (up to 1500 m per day) and long walking times (from 5 to 9 hours per day). DISCUSSION: This experience has enriched our reflection about the medical, functional, and psychological conditions required for this type of physical effort, both from patients and accompanying personnel. In the absence of reports on similar experiences with this patient population, we thought it interesting, six months after this challenge, to present our observations as well as the patients' point of view. This may encourage other rehabilitation teams to offer intensive walking activities for stroke patients.